Early onset affective and anxiety disorders are frequent and recurrent psychiatric disorders associated with significant morbidity and mortality. Anxiety disorders in children and adolescents are one of the most prevalent forms of psychopathology affecting as many as 10 percent of children. Estimates of the prevalence of Major Depressive Disorder (MDD) is 2 percent in pre-adolescent school aged children and 5 percent in adolescents. Increased risk for MDD is conferred by childhood anxiety disorders and a history of trauma (e.g. abuse). Within five years of the onset of MDD, up to 70 percent of children and adolescents with depression will experience a recurrence, and as many as 20-40 percent of the children will develop Bipolar I disorder. in addition, it is estimated that close to 5 percent of depressed adolescents will complete suicide within 10 years of their initial episode of MDD. Early onset affective and anxiety disorders frequently persist into adulthood, and functional impairment is greatest in adults who experienced the onset of these disorders in childhood. The Clinical Core is the gateway to the Center. It supports the overall goal of the Center of improving the life course of children, adolescents, and families with early-onset affective and anxiety disorders through research on assessment, phenomenology, correlates, and course. Specific foci of research supported in this Core include: improved assessment of risk factors for early onset affective and anxiety disorders (e.g. trauma); identification of factors associated with onset, course, recurrence, and transition to other disorders (e.g. pre-existing and comorbid anxiety disorders); and examination of predictors of treatment response (e.g. parental psychopathology, life events).